Anyone who has tried walking or running in water knows how much effort that can take compared to swimming. Just think about what a fish goes through!
On top of that, many fish live in turbulent waters. But over time, fish have made adaptations to conserve energy when swimming against the current. Researchers at Harvard figured out the underlying physics. They literally understand what it means to swim like a fish.
You see, when water hits objects like branches, rocks, or other fish, it forms strings of little whirlpools, or vortices. So researchers set up a tank with water flowing in one direction, and dropped a cylinder in it that generated vortices.
The researchers observed that rather than fighting the current, the fish simply slalomed between vortices, using a swimming style that resembles a flag flapping in the wind. The advantage of all the side-to-side movement is that it requires very little muscle activity. In fact, fish can use this technique to hold their position and rest while in rough patches of water.
These findings have applications ranging from technology to conservation.